1. Field of the Invention
The present invention relates to an image forming system which cuts a roll sheet to form an image by an image forming portion.
2. Description of Related Art
In recent years, the print demand has been changed. Print on demand (hereinafter, referred to as “POD”) for performing various small-lot prints has been increased in comparison with the demand for printing a large quantity of the same print matters. In the print demand like POD, cost and time loss are high in an offset printing apparatus which needs to make a printing plate and a screen for each print like a printing press. There have been great expectations for an electrophotograph image forming apparatus.
In the related art, many electrophotograph image forming apparatuses store recording sheets which are cut to a predetermined size such as an A system or a B system in a paper manufacturing process in a feeding deck and feed them one by one therefrom to perform image formation. Such feeding system is assumed to be used in offices and at home. As in the offset printing apparatus, when a large number of recording sheets are printed, they run out in the feeding deck immediately. A large-capacity feeding deck which increases a storable number of sheets has been typically known. The recent technical progress has been remarkable. The productivity of the electrophotograph image forming apparatus has been improved drastically. The problem that the sheets run out immediately even in the large-capacity feeding deck cannot be solved.
In recent years, it has been proposed that the problem is solved by multiply-coupling the large-capacity feeding decks. The problem that sheets to be fed run out immediately can be solved by multiply-coupling the large-capacity feeding decks. The cost for preparing for plural large-capacity feeding decks is increased. The entire apparatus is made larger.
As a method for solving these problems, there has been typically known a roll sheet feeding unit as seen in the offset printing apparatus, in which an uncut roll sheet is provided and is cut at the time of printing for feeding. An apparatus in which the roll sheet unit is attached to the electrophotograph image forming apparatus has been actually proposed (Japanese Patent Application Laid-Open (JP-A) No. 2005-250273).
The roll sheet feeding unit can produce recording sheets of which number is larger than that of the recording sheets previously cut. The frequency in which the sheets to be fed run out can be reduced. There is a merit that the cost for feeding the recording sheets can be reduced.
Japanese Patent Application Laid-Open (JP-A) No. 2007-136717 discloses a configuration which cuts a roll sheet so as to stack and store cut sheets in a storage portion and feeds the sheets from the storage portion to the image forming portion. The operation of cutting the roll sheet and feeding the cut sheets to the storage portion so as to stack them in the storage portion and the operation of feeding the sheets from the storage portion to the image forming portion cannot be performed at the same time. The productivity of the configuration of JP-A No. 2007-136717 is low.